The removal of bubbles from baths of liquid, is required in many industrial operations, to avoid the impairment of optical and strength properties of the finished products. One method described in U.S. Pat. No. 3,853,500 by Gassmann involves the application of acoustic energy resonant to a dimension of a liquid bath, to urge bubbles towards a node of the acoustic standing wave pattern where the bubbles coalesce. This technique is primarily useful in coalescing larger bubbles such as those above a millimeter in diameter, but is not as useful in removing submillimeter size bubbles. In addition, considerable time may be required for coalesced bubbles to float to the top of the bath, especially where the liquid in the bath is very viscous. In one specialized technique wherein the liquid is under zero gravity conditions (in outer space), the bubbles will not float to the surface.
In another technique, described in U.S. Pat. No. 4,205,966 by Horikawa, acoustic energy is applied to a bath to vibrate it, to help dissolve bubbles into the liquid of the bath. While this technique can help dissolve small bubbles, it still requires an inordinately long period of time to absorb such bubbles. Such a long period for absorption applies especially to bubbles in the range of 50 microns to 1000 microns. Such bubbles are too small to be easily moved together to coalesce, require very long term vibration of the bath to become dissolved therein, and yet are large enough to seriously affect the qualities of many products. A technique which enabled more rapid removal of bubbles of a wide range of sizes and under a variety of conditions including zero gravity conditions, would be of considerable value.